Duplex system



March 2,1943. w. G. H. FINCH DUPLEX SYSTEM- Filed. July 12, 1940 '9 Sheets-Sheet 1 P "1 I E T 5 H N u b! L,

a: N g '1 .5

- a: I I

INVENTOR.

WILLIAM 3. H. FINCH ATTORNEY.

March 2, 1943. w. s, H. FINCH 1 ,3

DUPLEX SYSTEM ..Filed July 12, 1940- 9 Sheets-Sheet 2 w flgm IIIIIIIIIIIII/IlIl/IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII FIG. 2

INVENTOR. WILLIAM cs. H. FINCH BY 2 z March 2, 1943. w. G. H. FINCH f "2,312,323

' DUPLEX SYSTEM Filed July 12, 1940 9 She ets-Sheet 5 Y INVENTOR.

F86 '7 WlLLIAM G. H. FINCH March 2, 1943. w. G. HQFINCH DUPLEX SYSTEM Filed July 12, 1940 Y 9 Sheets-Sheet .4

ATTORNEY.

March 2, 1943. w. e. H. FINCH 2,312,328

DUPLEX SYSTEM 1 Filed July 12, 1940 9 Shets-Sheet 5 FIG. l2 v F1613 FIG. I4

' INVENTOR. WiLLJAM C5. H. F'INCH ATTORNEY.

March 2,1943.

w. G. H. FlNCH DUPLEX SYSTEM.

Filed July 12, 1940 9 Sheets-Sheet 6 FlG.l6

' INVENTOR. WILLIAM G. H. FINCH BY A ATTORNEY.

March 2, 1943.

W. G. H. FlNCH DUPLEX SYSTEM Filed July 12, 1940 9 Sheets-Sheet '7 F'IG.I7

F'IG. l8

. INVENTOR.

WILLIAM G. H. FINCH BY z ATTORNEY.

' March 2, 1943.

W. G. H. FINCH DUPLEX SYSTEM Filed July 12, 1940 9 Sheets-Sheet 8 FIGLIQ F I G. 20 I NVENTOR.

Wll l .|AM G. H. F'JNCH WW ATTORNEY.

March 2, v1943.

' W. G. H. FINCH DUPLEX SYSTEM 9 Sheets-Sheet 9 Filed July 12., 1940 INVENTOR. WILLIAM G. H. F'INCH ATTORNEY.

Patented Mar. 2, 1943 VUNITED STATES PATENT OFFICE DUPLEX SYSTEM William G. H. Finch, Newtown, Conn.

ApplicationJllly 12, 1940, Serial No. 345,194

Claims (Cl.'1786.6)

My invention relates'in generalto the field'of facsimile transmission. and reception and'more specifically relates toa facsimile. unitin which the samegerie'ral mechanism may beemployed for both transmission andreception.

In facsimile transmission systems it is necessary to secure synchronism between the transmitter and receiver; This isiusually accomplished by rotating the receiver at a slightly greater speed than the transmitter and then bringing it to astop at apred'etermined position until the receipt of asynchronizing signal from the transmitter indicates the transmitter has arrived'at the same corresponding position, thus insuring thatboth the transmitter and receiver start each cycle of operations at the same position and maintain substantial synchronism throughout the cycle; I

The transmitter is provided with means for translating yariationsin lights and shades into electric-currents and this isusually accomplished by an" optical system and-photoelectric cell. At the receiver, on the other hand, the received electric impulses are translated b'ackinto the means for producing corresponding variations in lights and shades of the picture.

These and other features usually make the transmitterand receiver so different in construction and function that they have ordinarily been treated as;separate and individual mechanisms, each necessaryin the complete system.

In many instances-in facsimile transmission, as, for example, for airplane use, it is desirable tohave .two Way facsimile communications and yet theweight and space of the facsimile machine must be' kept to a minimum;

, Heretofore, it. has been regarded as essential, as, pointed out aboveto-employ in such-systems a separate transmitter and receiver.

-I have-discovered that I may employ a single Picture. fieldand bring into cooperation therewith a transmitting scanner and a receiving scanner cooperating with the picture field in suchamanner that it may act both as a transmitter'and alternatively as a receiver.

When acting as a transmitter it in the usual manner transmits synchronizing pulses to a remote receiver. When acting as a receiver it will start-stop in response to synchronizing pulses receivedfrom the remote transmitter.

Similarly, the picture field when cooperating with thetransmitter translates the variations in lights. and shades of the picture into corresponding currents andwhen'cooperating with the receiver translates the receivedpicture currents intocorresponding lights and shades on the picture.

, I have specifically illustrated my invention as applied to the drum type transmitter but it will be understood that other forms commonly employed in picture transmission systems may also be used.

Thus,-in the form I have selected fortillustrating my inventiona drum carries the image to ,be-transmitted or the recording sheet .on which the received picture is to be recorded and ,either one of two scanning members, one being fixed with respectto the drum and the other rotatable with respect to the drum, are employed.

, The recording unit ofmy invention employs a single drum upon which the electrochemically sensitive paper is mounted for receiving and upon which thephotograph or other picture is mounted for transmission.

For recording purposes, a conductive stylus is arranged to circumferentially traverse the surface of the drum in a circular manner while the drum itself does not rotate butismovedparallel to its axis and perpendicular to the plane of rotation of the stylus. Thus I secure the helical scanning motion required for recordingupon a sheetof paper mounted upon a drum.

For the transmissionv of images, my novel unit afiords means whereby the drum may be rotated about its axis while being displaced parallel theretoin order to again achieve the helical motion required, relative to a fixed beam of light.

The recording stylus ispivotally mounted on its carriage so that it may be juxtaposed against the recording paper during facsimile reception or .maybe; disengaged from thedrum during the transmission of images.

In. addition, the stylus carriage is slidably mounted within, an annular ring which is driven by the source of motive power andwhich will carry thestylus in fixed relationtherewith during the normal recording cycle.

The annular ring supporting the stylus is adjusted to rotate at a slightly higher speed than the stylus itself. Upon the receipt of a synchronizing impulse generated at the transmitter, the stylus is once more allowed to rotate with the annular supporting ring and traverse the circumference of the drum.

The annular ring comprising the stylus mounting forms an endless track about which the stylus may move. Thus if the stylus supporting ring is adjusted to rotate at a higher speed than the corresponding light beam stylus at the transmitter, the motion of the stylus will be arrested once during each revolution thereof.

In the recorder employing the endless chain type of stylus support, it was necessary to periodically rephase the position of the stylus relative to the support inasmuch as the stylus supporting tracks and guides could only be of relatively limited length. Therefore, as the effect of synchronization was cumulative due to the increased speed of the recorder, there was 2. danger of allowing the stylus to be withdrawn from its track after several minutes of recording time.

Thus, it was necessary to introduce a second synchronizing means which would reset the stylus at the beginning of its track subsequent to the recording of several inches of the picture.

However, in the present novel type of drum recorder, it is not necessary to rephase the stylus relative to the stylus supporting ring inasmuch as the supporting ring and guide track are in effect endless, that is, circular. v'I'hus, I secure the benefits derived from a synchronizing system in which it is necessary to merely arrest the small mass of the stylus and in addition overcome the diificulties encounted in the rephasing operation of previous machines.

It is an object of my invention to provide for a facsimile recorder and transmitter which may be combined into a single unit and which need only employ a single drum for both functions.

It is another object of my invention to provide for a stylus which is rotatable about a recording drum and which may be cyclically synchronized by the expedient of stopping the relatively small mass of the stylus itself.

It is a further object of my invention to provide for a mechanical system which alloys for both the rotation and axial movement of the drum relative to a fixed scanning means for transmission of pictures; and the axial movement alone of the drum relative to a scanning means rotating thereabout in a fixed plane for reception.

As it is necessary in facsimile recorders and transmitters to receive and generate synchronizing impulses respectively, I provide a series of cams mechanically coupled to the rotating elements which coact with a pair of switching elements to perform the required switching functions. However, as it is necessary for me to vary the type of motion of the drum during recording and transmitting, and as it is desirable to reduce the weight and over-all dimensions of the facsimile unit, I provide novel means whereby I may employ the synchronizing cams not only for switching purposes but also to limit and control the motion of the drum in accordance with the specific operation being performed.

Therefore, a further object of my invention is to provide means for generating synchronizing impulses in conjunction with means for selectively switching the received synchronizing impulses by a plurality of cams coupled to the driving means.

Still a further object of my invention is to construct the cams so that they may function both as synchronizing units and as controlling members for obtaining the desired drum movement.

These and other objects of my invention will become apparent from the following specification taken in connection with the accompanying drawings, in which:

Figure 1 is a plan view of the duplex machine of my invention.

Figure 2 is a cross sectional view of the facsimile recorder and transmitter taken along the line 2--2 of Figure 1.

Figure 3 is a fragmentary perspective view of my novel recording stylus support and guide rail.

. Figure 4 is a broken perspective view of the stylus carriage.

Figure 5 is a cross-sectional view illustrating various mechanical features of the optical system employed and is taken along the line 5-5 of Figure 1.

Figure 6 is a broken end view of the stylus support, drum and synchronizing lever, and is an enlarged fragmentary portion of Figure 5 illustrating the stylus in operative position.

Figure 7 is a cross-sectional view of the stylus carriage and the support therefor taken along the axis 1--'! of Figure 6.

Figure 8 is a View corresponding to that of Figure 6 illustrating the recording stylus in the inoperative or transmitting position.

Figure 9 is a broken cross-sectional view of the drum employed for both the reception and transmission of images taken along the lin 9-9 of Figure'l.

Figure 10 is an end cross-sectional view of the drum taken along the line Ill-J0 of Figure 1 and illustrates the means for obtaining axial displacement of the drum during recording.

Figure 11 is a view corresponding to that of Figure 10 illustrating the drum displacing means in the inoperative position.

Figure 12 is an enlarged cross-sectional view of the mechanical drive system (corresponding to the left portion of Figure 2) when employed for recording facsimile signals.

Figure 13 corresponds to Figure 12, showing the drive mechanism during the transmission of images.

Figure 14 is a view partly in cross-section of the clutch mechanism of Figures 2, 12 and 13 employed to mechanically switch the operation of the unit from a recorder to a transmitter.

Figure 15 is an end cross-sectional view of the driving mechanism taken along the line l5l 5 of Figure 2.

Figure 16 is a cross-sectional view of the clutch and operating means therefor taken along the line l6-l6 of Figure 15.

Figure 17 is an end cross-sectional view of the stylus operating means and drum taken along the line lI-ll of Figure 2.

Figure 18 is an end cross-sectional view of the switching means for generating synchronizing impulses taken along the line 18-48 of Figure 2.

Figure 19 is a cross-sectional view of a modified form of the driving mechanism of Figures 2, 12 and 13.

Figure 20 is an end cross-sectional view of the synchronizing cam taken along the line 20-20 of Figure 19.

Figure 21 is an end cross-sectional View of the modified driving mechanism taken along the line 2l2l of Figure 19.

Figure 22 is an end cross-sectional view of the modified form of driving mechanism taken along the line 22-22 of Figure 19.

Figure 23 is a cross-sectional view of the modified means for switching from transmitter to receiver operation taken along the line 2323 of Figure 22.

Referring now to Figures 1 and 2, there is shown a general view of the duplex facsimile arrangement in which the operating members are all mounted upon a single base 3| of suitable design. The single drum 32 which is employed for both the transmission and reception of images is operatively arranged with respect to the recording stylus 33 and the lamp housing 35 and optical system 34, and the photoelectric cell housing 35, so that these members may interact in the manner hereinafter described.

The source of motive power 35 (Figures 2 and mounted upon the frame by suitable brackets 31 (Figure 5') is coupled to the drum through the 'mechanical system housed beneath the base 3| and within the projecting metal housing 4| (Fig- -ure 1) fixed thereto by means of theplurality of screws 42 which pass through appropriate lugs upon the housing 4|.

The mechanical coupling system is completely enclosed within the housing 4| by means of the side cover plate 43 (Figures 1 and 2) which, however, is perforated at 44 to a allow for the passage of the feed screw and guide rods of the drum.

The feed screw 45 is driven by the motor 35 which is preferably of the synchronous type, and the necessary speed reduction is secured by means of the gearing contained within the housing 4%. The feed screw 45 is rotatably supported within two sleeve bearings, 4'! and 48. Bearing 41 is reamed into an integral projection of' the wall of the housing 4|; the opposite bearing 46 is formed in a corresponding projection 45 upon the wall of the opposite housing 5| mounted-upon the frame 3| (see Figures 1 and 2).

The housing 5| is secured to the frame by means of the bolts 52'which engage suitable projections or lugs 53 which have been integrally formed into the housing 5i. The housing 5| serves to shield the cam 54 which is loosely mounted upon the feed screw 45;

In order to perform the distinct operations of transmission and reception of images, the feed screw 45 must be maintained'in a stationary position for transmitting purposes and must be allowed to rotate under the influence of the driving motor 35 for recording purposes for reasons which will hereinafter more fully be described. This adjustable motion of the feed screw 45 is obtained through the gears contained within the housing 4| and the sliding toothedclutch which is operated by means of the hand lever 55.

The toothed clutch is formed upon the hub 51 (see Figures 2; 12 and especially 14) of a gear 58 which is driven by the pinion 6| which in turn is in fixed relation with respect to the motor shaft'62.

An annularv groove 63 which has been turned into the hub of the gear 58 is engageable with a bifurcated lever 64 having the tines 55 as is more clearly illustrated in Figures: 14', 15 and 16. The gear 58 is slidably and rotatably mounted upon the shaft 65-which is supportedby the two sleeve 65. The three gears 13, 5B and 12 are positioned upon the shaft 65 between the sleeve bearing 86 in the wall of the frame 3| and the collar 14 which is fastened-to the shaft 65 by means of the pin 15.

Gear 13 is maintained in fixed relation with the shaft 55 by means of the pin 16 which passes through the hub thereof and thus rotation of gear l3 will cause a corresponding rotation of the shaft 65.

It may therefore be seen that gear 58 when driven by .pinion 6| and when in the position indicated' inFigure 14, that is, having the teeth 1| bearings 55 and 6'! integrally formed into the main frame of the facsimile unit.

Referring now to Figure 1 the hub 5! of the gear 58 contains the two milled or otherwise formed sets of teeth which are engageable with corresponding teeth upon the two gears "and 13 which are alsomo'unted upon-theshaft in engagement with the corresponding teeth upon the gear 13 will cause corresponding rotation of the gear I3 and shaft 65.

The engagement between the teeth H as indicated in Figure 14 is obtained by turning the hand lever 55 of Figure 1 to the letter R (receiving) and thus causing the desired movement of the bifurcated lever 64' and the slidable' gear hub 51.

It should be. noted that when gear 58 is in the position indicated in Figure 14, sufficient clearance is allowedbetween the teeth I on the hub 5! and the corresponding teeth on the gear 12 to preclude interference therebetween.

However, movement of the hand lever 55 to the position indicated by the letter T (transmitting) of Figure 1 will accordingly cause motion of gear hub 5"! so that the teeth 1 I will be engaged with the corresponding teeth upon the gear 12 while providing clearance between the teeth H and the corresponding teeth on the gear 13.

The linkage between theliand lever 55 and the gear hub 5'! maybe of the form indicated in Figures 1'5 and 16, that is, rotation of the operating lever 55 will cause similar rotation of an eccentrically mounted circular cam 8i which is positioned upon the shaft 82 fixed to the lever 55 in any convenient manner.

The bosses 83 and 84 formed upon the casting of the frame 3| provide, when perforated, a suitable bearing for the shaft 82. The rotation of i the eccentric 8| takes place between the tines 85-85 of the bifurcated member 85 which is slidably mounted upon the shaft 81' which in turn is fixed between a boss 9| on the frame of the facsimile unit and a corresponding bearing 92 which is an integrally formed projecting lug.

A protrusion or lug 93' of the bifurcated member '86 carries the bifurcated member 54 which is in engagement with the annular groove 53 on the hub of the gear 58.

During the assembly of thefacsimile unit, the bifurcated lever 64' is first engagedwith the slot on the gear hub and is then fastened to the lug 93 by'means of the plurality of screws 95' which pass through-aligned tapped perforations in both members.

Therefore, rotation of. the eccentrically mounted circular member'Bi aboutits supporting shaft 82 which" is maintained. in fixed positionwith respect to the frame will cause the bifurcated member 85 to slide along the shaft 81 and thus similarly operate the'slidablegear 58;

The tines 8595 of the bifurcated lever 64 supported upon the gear hub' 5l, preclude rotation of the member 36 about its shaft, while allowing the gear 58 to rotate about the shaft 65 without deis/eloping undue frictional forces within the groove Obviously the clutch mechanism on the gear58 'and'the operating lever55 and its associated linkingmembers may'b'e replaced by any of the well known types of sliding clutches which are engageable with several gears.

When the clutch is in the position illustrated in Figures 14 and 16, the duplex facsimile unit is in condition for the reception of facsimile im- This may engagement with those on gear 13 which in turn is pinned to the shaft 65, shaft 65 will rotate and in addition, the gear IIII which is in engagement with the gear I3 will rotate again at a reduced speed due to increased diameter.

Gear IDI is fixed relative to the feed screw -46 and is maintained thus by means of the pin I 02 which passes through the gear hub and through a similar perforation in the shaft.

Also mounted upon the shaft of the feed screw 46 and contained within the housing M are the cam I03 and the gear I04. These are positioned within the housing between the face of bearing 41 and the shoulder I which has been turned into the shaft.

Rotation of the gear IOI, which will occur when the clutch is in the position of Figure 12, will correspondingly result in rotation of the feed screw 46 and the cam I03 which has been fixed thereto by means of the pin I66. However, gear I04 upon which are mounted guide shafts III and H2 does not rotate during the rotation of feed screw 46 for reasons which will hereinafter be described.

Also it will be seen that the fixing of gear I04 will maintain the drum 32 in a position which will preclude rotation relative to the frame of the facsimile unit. However, rotation of the feed screw will cause the drum to move axially at a rate which will be determined by the speed of the motor.

This is more clearly illustrated by Figures 2, 9, and 11 and reference is now made thereto. The two parallel, diametrically spaced guide rods III and H2 pass through the circular side walls H3 and H4 of the drum through corresponding diametrically spaced perforations therein. In addition, the feed screw 46 which, as indicated in Figure 9, is not threaded for the full length, passes through the circular side walls and in cooperation with the guide shafts H3 and H4 serves to position the cylindrica drum. The drum in itself is formed from a sheet of metal bent into the form of a cylinder H5 which is then mounted upon the two turned side walls H3 and II 4 and positioned thereon in the recesses H6 and II! respectively.

The side wall 3 of the drum contains a central sleeve bearing I I8 which is slidably and rotatably fitted over the unthreaded part of the feed screw shaft 46. However, the perforations I 2| and I22 within the side wall H3 are of sufficient diameter to provide clearance for the guide shafts III and H2 which extend from their fastening upon the gear I04 to their fastening upon the cam 54 which is contained within the oppositely positioned housing 5|.

The perforations I23 and I24 within the side wall I I4 are lined with a metal suitable for bearing surfaces and the guide shafts III and H2 are slidably fitted therein. Thus when the drum is in the position indicated in Figure 9, it is sup- .ported upon the guide shafts III and H2 by the bearings I23 and I24 and upon the feed screw shaft by the sleeve bearing H8.

Axial motion of the drum parallel to the shaft 46 is obtained by allowing lever I25 which is pivotally connected to the side wall II 4 of the drum by means of the shoulder bolt I26 to come in contact with the screw threads I2! which have been cut into the shaft 46.

The circular segment I3I has been cut into the lever arm I25 and has been threaded to engage with the threads I2'I. Lever arm I25 is biased towards the shaft 46 by means of the spring I32 connected thereto and which is fastened to the side wall II4 of the drum by means of the pin I33.

It is possible, however, to manually remove the lever I25 from engagement with the screw threads I21 by actuating the member I34 which is an integral part of the eccentric I35 which in turn is pivotally mounted upon the side wall II 4 of the drum by means of the shoulder bolt I36. In Figure 10, the lever I34 is in a position for allowing the lever arm I25 to contact the screw threads I21 under the influence of the spring I32.

Figure 11 again illustrates the side wall II4 of the drum but in this view the eccentric I35 has been rotated by means of the lever I34 and as illustrated, the lever arm I25 has been disengaged from the screw threads on the drive shaft 46.

The shoulder bolt I26 precludes a motion of lever arm I25 other than rotation about its pivot and thus when the screw threads are in engagement as indicated in Figure 10, rotation of the feed screw 46 will result in relative axial motion between the drum and the feed screw. Dependent upon the direction of rotation of the motor, and the direction of the axial drum displacement desired, the threads I 21 of the feed screw may have to be cut as left hand or right hand threads.

It is necessary to preclude rotation of the drum which may be a result of frictional forces developed at the surface engagement between threads I3I and I21,

Thus as will be hereinafter described, the parallel guide rods I2I and I22 are maintained in a stationary relation with respect to the frame 3I in order that rotation of the feed screw will not cause corresponding rotation of the drum but permit only axial displacements thereof.

Therefore, when the toothed clutch is in the position indicated in Figures 2 and 12, the drum will progress axially without rotation about its axis. From the general view of Figures 1 and 2, it may be seen that the length of the shaft 46 must be at leasttwice the length of the drum and must in addition provide additional space for the mounting of the gears and the insertion of the shaft into its bearings. The dashed lines in Figure 1 indicate the limits of the drum travel.

Inasmuch as the motion of the stylus is limited to a plane perpendicular to the axis of the drum as will hereinafter be pointed out, the helical recording motion must be attained by axial displacements of the drum. Therefore, if the stylus is to traverse the complete length of the picture, it will be necessary to provide a feed screw of length sufiicient to accommodate the entire drum.

The parallel guide rods III and H2 may be in Figure 18, rod

maintained in fixed space relation with respect to the frame 3I of thefacsimile unit when the clutch is in the position indicated in Figures 2 and 12 by suitably locking them or otherwise fastening them thereto. Howevenas my duplex machine is designed to be as compact as possible and to eliminate as much as possible needless, weighty parts, I employ the cam 54, upon which the two guide rods are fastened by nuts MI and I42, as a locking device against reverse motion of the parallel rods. The manner in which this is accomplished is best illustrated by the cross-sectional view, Figure 18, of the cam housing.

The cam 54 is a plate of metal and contains the notch I43, which during the transmission of facsimile images is employed in conjunction with rod I44 and switch blades I45 and I46 for the generation of synchronizing impulses. Inasmuch as the tendency towards rotation of the rods I I I and I I2 and their associated mounting plate or cam 54 is in the direction opposite to that required for the transmission of facsimile impulses, the notch I43 and the rod I44 may be employed to lock the cam 54 in place and thus prevent any reverse motion thereof.

In the embodiment illustrated in Figure 18, the rod I44 slides smoothly within a housing formed by drilling out a hole I41 in an integrally formed protrusion II of the housing 5|. The rod I44 is prevented from turning by the key pin I44 which slides in keyway I41 in the bore I41.

The rod I44 is biased towards the center of the shaft 46 by means of the leaf spring I45 which also serves as a switching member in that it carries contact I52 in a position where it may cooperate with a contact I53 mounted .upon the metal arm I46. Both arms I45 and .I46 are separated by a layer of insulating material I54 and the entire assembly is fastened to the frame by means of a plurality of bolts I55 which in turn are insulated from the frame 3| of the facsimile unit by the insulating layers I56 and I51. When the cam is in the position illustrated I44 is forced into engagement with the notch I43 and the contacts I52 and I53 are in surface engagement with each other. Thus, any electrical circuit connected' to the metal members I45 and I46 will be closed.

'If the cam 54 is rotated in the the arrow head indicated in Figure 18, the rod I44 will slide Within the bore I41 as the rod I44 rises along the notch I43. Upon reaching the outer edge of the cam '54, the rod I44 has been displaced sufficiently to open the contacts I52 and I53 and thus break the circuit into which they are connected.

However, it may be seen that the edge I6I of the cam notch I43 has been cut radially and thus any tendency towards rotation in a direction opposite to that indicated by the arrow head of Figure 18, will be arrested by the juxtaposition of rod I44 and face I6I of the notch I43.

As previously described, when in the position indicated in Figures 2 and 12, the clutch teeth 1I will engage the gear 13 which is pinned to the shaft 65 and thus will cause rotation thereof in the direction indicated by the arrow head of Figure 12.

I The shaft 65 is rotatably carried in the sleeve bearings 66 and 61 formed into the frame 3| and ispositioned thereon by means of the collar I 63'which is fixed thereto by means of the pin direction .of.

Also secured to the end of shaft 65 is a clearly illustrated in Figures I64. gear I65 which is ,9and17.

Referring now to Figure 9, it may be seen that the gear I65 is an annular member fastened by means of a plurality of rivets I66 to an insulating bushing I61 which in turn is secured to the shaft by means of pin I 1 I.

The insulating bushing I61 is drilled out at I12 to slip over the shaft 65 and contains the annular projection I13 to which the gear is fastened. Thus it should be noted that the gear I65 is electrically insulated from the frame of the facsimile unit, for reasons which will hereinafter be described.

Gear I65 is in engagement with a larger annular gear I15 which in this embodiment completely surrounds the drum 32 and which is supported on suitable brackets as will now be described.

An annular member I16 also surrounding the drum is fastened to the frame 3I of the facsimile unit by means of brackets I11-I11 oppositelyspaced as indicated in Figure 17. These brackets are carefully oriented upon the frame by a plurality of machine screws I8I which are insulated from the brackets by means of the fiber or other insulating spacers I82 and the brackets I11 are in turn insulated from the frame by means of the spacers I83 of insulating material.

As indicated in Figure '2, these brackets I11 do not interfere or in any Way impair the free motion of gear I15. The annular ring I16 is supported on the brackets by a plurality of bolts I85 which are suitably spaced around the periphery thereof and which position the annular member I16 so that it is coaxial with the shaft 46.

As indicated in Figure 9, the cross-section .of the annular member I16 is such as to provide a ring shaped projection I81 which acts as a track for the gear I15 and its associated apparatus. That is, an assembly is built up of gear I15, annular member .I9I and annular member I92 as indicated in Figure 9, and these members are maintained in rigid relation with respect to each other by means of a plurality of bolts I93 passing through cylindrical openings I94 provided by corresponding perforations within each of these members.

The members I9I and I92 provide, when assembled as illustrated, a T-shaped groove I95 which due to the symmetry of the circular members is in itself circular and thus in effect endless.

Furthermore, if during assembly of the facsimile unit, annular members I9I and I92 are first fastened to each other and are then joined to annular gear I15 after the annular gear I15 is placed in juxtaposition with the annular projection I81 of the fixed member I16, the composite assembly of the three members I15, I9I and I92 will be rotatable about the fixed member I16, provided that the frictional forces along the juxtaposed surface I96 and I91 are not excessive.

Thus it should be noted that rotation of shaft 65 will correspondingly rotate gear I65 and annular gear I15. Therefore rotation of shaft 65 will result in rotation of the composite annular ring formed by the members I15 and .I9I and I-92, about the axis of the drum. It should also be noted that in this embodiment of the invention, it was necessary to perforate the frame 3i at 2M in order to provide clearance for the composite annular ring and to allow for engagement of the annular gear I with gear I65.

As will now be described, the circular T- shaped track I95 formed between members I9I and I92 serves as a guide rail for a stylus carriage 202 as illustrated in Figures 3 and 4.

The carriage 262 is a metal member formed to correspond with the T-shaped track and is curved as a segment of the circle of the track. Thus the member 232 has projections 283 and 234 to engage the T-shaped track and also contains a body of metal 205 which carries the stylus and the stylus assembly itself.

The stylus holder 233 is a metallic member perforated at 231 as illustrated in Figure 4 and in the cross-sectional View of Figure 7. This perforation 201 allows the passage of a shoulder bolt 208 which rotatably supports the stylus upon the stylus carriage 232. In the embodiment illustrated, the stylus 33 is fixed to the holder 236 within a slot 2I2 which has been formed therein. The metal on either side of the slot is clamped together about the stylus 33 by means of the pin and set-screw 2I3 which passes through tapped perforations therein and which may be adjusted by means of an ordinary wrench. Also fastened to the set screw 2I3 is an overcenter spring 2I4 which is also connected to the stylus carriage 232 through a pin 2I5. Thus, when the stylus is juxtaposed against the paper as illustrated in Figure 6, the line of action of the force of the spring 214 is such as to maintain the juxtaposition thereof. However, if the stylus carriage is rotated manually or by any other means about its pivot, shoulder bolt 238, the stylus will arrive at the position indicated in Figure 8 wherein it may be seen that there is no contact between the stylus and the drum.

Furthermore, the rotation of the pin and set screw 2I3 in this process has moved the line of action of the spring over the center of the pivot and thus the tendency is to maintain the stylus in the position indicated. Obviously, this provision is made for converting the unit from a recorder (position indicated in Figure 6) to a transmitter (when the stylus is moved to the position indicated in Figure 8).

The pivotal mounting of the stylus 53 will greatly facilitate its accommodation to irregularities in the recording paper, particularly to the seam 214.

Referring now to Figures 3 and 7, the stylus carriage 202 is mounted slidably within the T- shaped track I95 during the assembly of the composite annular rings I9I and I92. The depth of the T-shaped slot I95 is somewhat greater than the depth of metal of the projections 203 and 234 and thus clearanceis provided at 22I as shown in Figure 7 between the rear of the stylus carriage and the face of the T-shaped slot. This clearance, however, is taken up by means of a bent leaf spring 222 which is fastened in any suitable manner to the face 223 of the stylus carriage and which bears against the rear face of the T-shaped slot I95.

Thus the stylus carriage is forced into juxtaposition with the track formed by the T-shaped slot along the wall 225, and the frictional engagement therebetween is sufficiently great to ensure that rotation .of the composite annular ring formed by the annular gear I15 and the track members will ensure corresponding rotation of the stylus carriage.

i In addition, the frictional retarding forces de- 7 veloped betweenthe stylus 33 and thepaper 226, which may be mounted upon the recording drum by means of the two garter springs 221 and 228, will not cause relative lipping between the stylus carriage and the track members However, I provide synchronizing means for arresting the motion of the stylus carriage, and thus the stylus itself. In this embodiment, the synchronizing means assumes the form of a lever arm 23 I, pivotally mounted by means of the pin 232, as illustrated in Figure 5. The pin 232 is carried Within a bracket 233 which is in turn fixed to the frame 3I of the facsimile unit and which is insulated therefrom by suitable insulating material such as fiber, Bakelite or the like.

One arm 235 of the lever 23I carries a piece of magnetic material 236 and'is of suitable length so that the magnetic material 236 is supported over the synchronizing magnet 231. The magnet 231 itself is carried upon an integrally molded protrusion 238 which is reinforced by the rib of metal MI and which carries the magnet supporting cross-arm 242 by means of the plurality of machine screws 243. Thus electromagnetic attraction between the core 244 of the magnet 231 and the magnetic material or armature 236 will cause rotation of the synchronizing lever 23I about the pivot 232.

The second arm 245 of the lever 23I projects through a perforation in the housing of the facsimile unit 3 I, and is in the plane of the stylus carriage 202. When in the position illustrated in Figure 5, (no attractive force between the core 244 and the magnetic material 236) the lever arm 245 is biased so that it engages the stylus carriage at the junction of the surfaces 246. The biasing of the lever may be produced by suitably weighting the lever arm 245 or by a small spring oriented to produce clockwise rotation of the lever arm 23I when viewed as in Figure 5.

The faces 245 of the lever arm 245 and the stylus carriage 202 are polished in order to ensure a minimum of frictional resistance therebetween and therefore upon energization of the synchronizing magnet 231 the faces 246 will easily separate and allow clearance for the rotation of the stylus carriage 202. The action of the synchronizing lever arm is more clearly illustrated in the enlarged view of Figure 6 wherein the lever arm 245 is first represented by a solid line to indicate the normal position towards which the biasing spring or other means tends to position the arm. However, upon receipt of the synchronizing impulse, and energization of the magnet, the lever arm 245 will move in the direction of the arrow head to the position indicated by the dashed line and it may be seen that suflicient clearance is allowed for the normal rotation of the stylus carriage.

Thus the motion of the stylus carriage 202 will be unimpeded and will be carried along by the annular ring by the frictional engagement therebetween until the lever arm 245 comes into engagement therewith. At this point, relative rotation between the annular ring and the stylus carriage will begin immediately inasmuch as the stylus carriage 202 is held in a fixed position and the annular ring is being positively driven by the source of motive power. A proper adjustment of the frictional forces exerted by the leaf spring 22I will preclude the possibility of excessively loading the motor or generating excessive heat due to the frictional contact therebetween.

In the present day facsimile recorders and transmitters, synchronism is effected by'means of an impulse generated at the transmitter prior to the commencement of a scanningscycle. This impulse may be in the form of an increase'of amplitude or a signal of a distinct frequency as described in my copending application Serial No. 203,222, filed April 21, 1938.

In order to preclude the recording of the synchronizing impulse upon the electrochemically sensitized paper, I provide switching means at the receiver to selectively separate synchronizing impulses and picture signals.

In this embodiment of my invention, I accomplish this by means of a cam I03 which is fixedly mounted upon the shaft 45 as illustrated in Figure 15. A notch 25I in the cam coacts with the slider rod 252, which is slidably positioned within a cylindrical sleeve bearing 253 formed by suitably drilling or reaming an integrally molded lug 254 of the housing 4|. The rod 252 is prevented from turning by the key pin I52 which slides in key way I54 in the bore 253.

The rod 252 is continuously biased towards the center of the shaft 45 by means of a spring which in this embodiment of my invention is the leaf of metal 255 of the synchronizing switch. When in the position illustrated in Figure 15, the rod 252 has been displaced into the notch 25I and contacts 255 and 251 on the leaf of metal 255 and 26I respectively are in juxtaposition and thus an electrical circuit connected thereto will be closed.

However, rotation of the cam I03 in the direction indicated by the arrow head in Figure 15, (which is the direction of rotation during receiving) will bring rod 252 up upon the circular edge of the cam and thus displace leaf 255 to close contacts 262 and 263 mounted upon the leaves 255 and 254 respectively.

The metal leaves of the switching member are separated from each other by insulating layers 265 and 256 which in turn are fixed to the frame by a plurality of screws 259 insulated therefrom by means of insulating layers 251 and 268.

The cam I03 is positioned upon the shaft 46 so that the rod I52 is actuated prior to the in.- ception of a synchronizing impulse. Actuation of rod 252 connects the incoming signal from the recording stylus to the synchronizing magnet and the electrical filter which is associated with the synchronizing magnet, if the magnet is operated by one distinct frequency.

Immediately after the reception of the synchronizing impulse and the movement of lever arm 245, the rod 252 again connects the incoming signal to the stylus due to its rise upon the edge of the cam I53.

The notch 25I of the cam I03 has been cut with a radial face 21I to engage with the edge of rod 252 as seen in Figure 15. Thus it is obvious that reverse motion of cam I03 is impossible (this will be more fully described in relation to the transmitter operation of my duplex facsimile machine).

Summarizing now, the operation of my machine as a recording device is as follows: The sensitized paper is first mounted upon the drum by means of the garter springs 221 and 228 and the lever arm I25 fastened to the wall of the drum I I4 and containing the segment of the nut I3I is raised and the drum is then slidably moved to the left as viewed in Figures 1 and 2 to the beginning of the threaded portion I21 of the shaft 45. Here rotation of the eccentric I35 again allows engagement between the segment of .the nut I3I and the screwthreads I21..

The hand lever .I 55.is.moved to the .positiomR indicated in Figure land thus t e to th d clutch out upon the gear hub I51 is displaced to the position indicated in Figures 2 and 12. The stylus support 205 is rotated to the position indicated in Figure 6 so that the point of the stylus 33 is in juxtaposition with the recording paper.

The incoming signal is impressed between the stylus and the conductive drum and the motor is energized. This results inrotation of shaft 65 and shaft 45, while guide rods III and H2 are fixed by cam 54 and rod I44 to prevent rotation of the drum.

Thus the engagement between the segment of the nut I3I and the threaded portion I21 of the shaft 45 will result in an axial displacement of the drum to the right as viewed in Figures 1 and 2. In addition, the rotation of shaft 65 and its attached gear I55 will cause rotation of the composite structure of the annular gear I15 and the track members ISI and I92 about the center of the shaft 46. The direction of rotation of the annular composite ring is such as to carry the stylus in the direction indicated by the arrow head of Figure 6 and it should be noted that the overlapping portions of the paper 214 are fixed to preclude interference with the stylus.

Continued rotation of the stylus and the composite annular members will result in a helical scanning of the recording drum. However, at the termination of each circular scanning excursion, the stylus carriage 202 is arrested by means of the lever arm 245 which has been placed in the path thereof.

In order to ascertain that the stylus will arrive at the face 245 of the lever arm prior to the arrival of the scanning stylus at the transmitter at the corresponding point, the composite annular ring is driven at ;a slightly higher speed.

If synchronous motors are employed at both transmitting and receiving ends, this slightly higher speed may be attained by making the tOObh ratio of gears I15 to gear I55 slightly less than a corresponding ratio at the transmitter. If nonsynchronous motors are employed, the receiving motor may be governed to a slightly higher speed.

Thus once during each circular cycle, the stylus carriage and its associated stylus will be allowed to rotate relativeto the annular supporting members and it is important to note that the mass of .the stylus carriage which is stopped is relatively small as compared to the mass of the-ann-ular gear and track members and their associated driving members.

Upon the receipt of a synchronizing impulse, the stylus carriage 252 will immediately be freed and rotation without relative slipping between the stylus and the annular track members will :be resumed.

The screw threads I21 are cut so that the drum progresses as required by the picture being ;received and in most instances is designed to progigelss of an inch per revolution of the shaft This therefore produces one :hundredscanning lines per inch. If, however, greater definition is desired and is justified by the recording and transmitting means, the screw threads I21 may be appropriately machined.

The cam 54 and its integral notch I43 prevent, as previously described, motion of the drum due to the frictional forces developed at :the engagement between the segment of the nut I3I and the screw threads I21.

Upon the completion of the ;pictu re,-the se ment of the nut I3I will, haveh lqgressed toih point 29I on the shaft 45 whereat the threads I21 have been terminated. Thus the segment of the nut will cease to act upon the drum and axial displacement thereof will also be terminated.

It may be seen that the stylus carriage 202 will be displaced somewhat relative to the annular track members at the termination of each scanning cycle. This displacement is due to the need for synchronizing the transmitter and receiving devices. However, as the T-shaped track I95 is in effect endless, that is, circular, the displacements of the stylus carriage within this track will have no effect upon the following cycle, that is, it will not be necessary to reset the stylus to its original position during each circular scanning cycle.

However, if the transmitter and receivers are operating from power supplies which are not interconnected or if the devices are operating at different speeds as required by the synchronizing means, the displacement of carriage 282 within the track I95 will be cumulative and its relative displacement with respect to the notch 25I of the cam I03 will be additive for each succeeding cycle.

After the completion of several hundred scanning lines, perhaps, the stylus could be rephased relative to the cam, similar to the styli of my multi-stylus recorder, as indicated in my application Serial No. 334,404. If, however, the synchronizing switch were actuated by the stylus or the stylus carriage itself, there would be no such progressive displacement and therefore synchronization may be effected by continuously displacing the stylus with respect to its supporting trackwithout the need for rephasing the stylus with respect to the switching cam. 1

In order to operate my duplex facsimile machine as a transmitter, I actuate the hand lever 55 to the position T indicated in Figure 1 and thus cause the eccentric BI (Figure 16) to operate the bifurcated lever 64 and engage clutch teeth 'II' with the corresponding teeth upon the hub of the gear I2 while allowing clearance between the clutch teeth 'II and the corresponding teeth on the hub of the gear I3.

Figure 13 indicates the clutch when moved to the transmitting position. As the gear I2 is free and rotatable with respect to the shaft 6 5, the engagement during the transmitting position will not result in rotation of shaft 65 other than that which may be due to the slight frictional forces between the gear bearings and shaft itself.

However, rotation of gear I2 will cause rotation of idler gear 30I which is rotatably supported upon the shoulder bolt 302 that is fixed to a lug 303 of the frame 3|. The idler gear 30I which is in toothed engagement with. gears I2 and I04 is interposed to merely reverse the direction of rotation of gear I04.

Gear I04 which is rotatably mounted upon shaft 46 carries fixed thereto by means of bolts 304 and 305 the two parallel guide rods III and IIZ and thus rotation of gear I04 will result in a positive rotation of the drum 32.

However, this rotation of the drum is opposite to the direction of rotation of the shaft 46 which resulted from the motion of hand lever 55 to the position R. of Fi If now the shaft 45 is maintained in a fixed position and rotation thereof is prevented and if the segment of the nut I3I is allowed to engage screw threads I21, the drum while rotating will once more progress axially towards the right as viewed in Figures 1 and 2.

' separating and generating cams.

chronizing impulse.

Th frictional engagement between rotating gear I04 and shaft 4'6 is such that there is a tendency to drive shaft 46 in a direction opposite to that while receiving. Therefore, as previously mentioned, the notch 25I of the cam I03 will engage the rod 252 at face 2' and prevent such reverse motion.

In addition, the rotation of the parallel rods III and H2 in the direction indicated will allow free rotation of cam 54 and thus during each cycle of rotation the contacts I52 and I53 will open and reclose.

During transmission, the image is again mounted upon the drum by means of the garter springs 22'! and 228 but the recording stylus 33 is moved to the position indicated in Figure 8 to preclude engagement with the face of the picture.

At this point, the lamp 3II contained within the housing 3I2 which is of a suitable design, and may be of the type indicated in my application for patent Ser. No. 318,230 is illuminated and a spot of light is focussed by the optical system 34 upon the face of the image to be transmitted. The optical system of this unit is carried by the cylindrical bearing 3I4 which is mounted upon the frame 3I of the unit at 3I5.

The necessary adjustments of the lamp housing and the optical system are secured by slidably adjusting the relative position of lamp and optical system in the sleeve bearings 3I6 and 3I'I. The set screw 32I serves to fix the optical system after adjustment.

The beam of light as reflected from the surface of the image to be transmitted is converted to corresponding electrical impulses by the photoelectric cell in housing 35 and the level of the signal and light beam intensity may be adjusted by the controls 32I contained on the sloping face of the panel 3 I.

The helical scanning required is obtained by maintaining a fixed beam of light and rotating the drum about its axis while it also is displaced axially. At the termination of each scanning cycle, the rod I44 operates the switch contacts I52 and I53 to generate the required syn- The electrical connections to the synchronizing impulse generator may be similar to those illustrated in my aforementioned patent.

Thus it may be seen that by operating the hand lever 55 in the direction T, I may convert my unit from a facsimile recorder to a transmitter and thus it is quite obvious that it has considerable application in military, police and work of a similar nature.

I may, of course, employ my improved synchronizing means on a unit which merely contains the gears and apparatus necessary for the reception of electrical impulses. Therefore, I may eliminate the transmitting synchronizing impulse generator and the lamp housing and photoelectric cell and their associated electrical connections.

As has been previously described, it is necessary to prevent rotation of the drum during recording while it is necessary to prevent motion of the feed screw during the transmission of facsimile pictures. In the foregoing I have described a means for preventing these undesirable motions by utilizing the synchronizing impulse In addition, I have devised a modified form of driving mechanism which may be employed in conjunction with my duplex machine and which is especially adapted to the unit in which I mount the synchronizing switch in operative relation with the stylus, and is'illustrated by Figures 19 through 23.

Figure 19 indicates that the driving motor 36 drives a gear 321 through a pinion 32 2 fastened to the drive shaft. Instead of the toothed clutch which was cut into both sides of the hub of the gear 58, illustrated in Figur 2, the .hub of the drive gear 321 contains two indentations 323 and 324 (Figures 21 and 22) which may engage the pawls 325 and 326 as will now be described.

The shaft 65, which again operates when rotating the annular stylus drive gear 115, carries the gear 321 and two additional gears 331 and 332 and the three gears are positioned on the shaft between the bearing 66 and the collar 14 as in Figure 14 of the previously described mechanism.

Gear 332 is secured to shaft 65 by means of the pin 333 while gear 331 is allowed to-rotate freely thereon and is therefore lined with a suitable bearing material 333. When gear 332 is driven, shaft 65 will rotate and also will drive the two idler gears 335 and 336 which transmit the power to the gear 331 which is secured by means of pin 331 to the feed end screw 46.

Rotation of gear 331 will not cause rotation of shaft 65 but will, however, drive idler gear 341 which is rotatably secured to the frame by means of shoulder bolt 342 and which will in turn drive gear 343. Gear 343 is freely and rotatably mounted upon shaft 46 andcarries the two parallel guide rods I11 and 112 by means of bolts 364 and 335. It is apparent that gear .343 will rotate in a direction opposite to that of gear 331 inasmuch as gear 331 is driven from the same source of power through the two idler gears and gear 343 is driven through one idler gear.

Mounted upon gears 331 and 343 are two cams 344 and 345 which are merely sheets of metal perforated at 343 and 341 respectively in order to pass over the hubs of their respective gears. The cam 344 has been fastened to the gear v.331 by a plurality of rivets 351 while cam 345 utilizes the bolts 334 and 305 for adequate support.

The gears 331 and 332 carry the rotatable pawls 325 and 325 respectively by means of shoulder bolts or rivets 352 and 353 respectively and each is normally biased towards engagement with the notches which have been out into the shaft, by means of the biasing springs .3154 and 355. The position of these pawls, however, is also determined by the operation of lever arms 361 and 362 which are pivotally mounted upon a shaft 363 or any other suitable rotatable mount.

. As illustrated in the sectional view, Figure 19, the lever arms rest on the pawls 325 and 326 and are adjacent the gears 331 and 332. The peculiar shape of these lever arms is determined by the particular gears about which they must operate and thus the circular segments 364 have been removed from the face of the lever in order that they may provide clearance for the gear and for the pawl. The lever arms are operated about their pivot 363 by two eccentric circular disks 365 and 366 which are fixed upon a shaft 361 by means of pins 368 and 311 and the entire shaft is operable by means of a hand lever '312 which projects from the housing 3| .as indicated in Figure 23.

The shaft 361 is rotatably mounted within a bearing 315 which has been formed asan integral projection of the wall of the housing and similar bearing 3.16 which has been drilled or reamed into a protrusion 311 .of the housing wall.

Rotation of the handlever through 180 .Will

therefore lift one lever and lower the otheras indicated in Figure .21.. The levers are biased by means of springs 381 .and .382 towards their respective eccentric circular disks.

When the hand lever is .in the position shown in Figure 23, the member .362 .has been raised and thus the circularsegmen-t364 clears theedge of the pawl 326 and allows .thebiasing spring 355 .to force the pawl into the =eng-ageable slot 324. On the otherhand, lever arm361 as illustrated in Figure 21 has been allowed ,to descend under the action of its biasing spring .382 and as illustrated, the circular segment364 has engaged the awl 325 and rotated it against the action of the biasing spring 354 and thus the edge of the pawl clears the engageable notch 3,23 and will allow free rotation thereof.

In this position, therefore, the hub ofthe gear 321 which contains the notches 32-3 and .324 will engage the pawl 326 and cause rotation .of the gear 332 to which the pawl has been riveted .or otherwise fastened. Rotation of .gear .332

through the idlers 335 and 336 will cause rotation of the gear 331 and the attached shaft 46 and if the segment of the nut 13.1 is .in screw thread engagement with the shaft 46 corresponding axial displacement of the drum will result.

In addition, the rotation of gear .332 will .drive shaft 65 and thus drive .therotatable stylus support as has beenpreviously-described. With this modification of my invention, the reverse motion of the drum due to the frictional engagement at the screw threads 1-21 and 131 .is prevented by an additional function of the lever arm .361. That is, from Figure 21 it may beseen that the extension 385 of the lever arm361 has engaged a notch 3.86 within the cam 34.5.

Obviously, if upon the rotation of thejlever 312 to the position shown, the extension 385 doesnot exactly correspond with the notch 336., then the drum will rotate somewhat until these two do correspond and immediately then the spring 332 will cause engagement thereof.

With this type of driving mechanism, I need not .cut the cams 54 and 1113 to act as both switching members and stops for any reverse motion. Thus, .as illustrated in Figure 20., .the cam 39.1 employed to selectively separate the incoming synchronizing and .picture impulses is mounted upon the gear 3.3.1 and the locking cam .344 and coaxial therewith. The notch 392 of the cam 391 is smoothly out to ensure free cooperation with the rod 393 which operates the switching members.

When the lever arm 312 is turned from the position illustrated in Figure 23, through the position of lever arms 3'61 and 362 will be effectively interchanged. Thus the pawl. 326 will be disengaged from its mating notch 324 in the gear hub and the pawl 325 will be allowed to effect engagement under the influence of its biasing spring 354. Also this rotation will free lever arm extension 385 from the corresponding notch386 on the locking cam "3'45 and will cause the engagement of extension 395 on lever arm 362 with a cam-344 which is mounted upon the gear 331.

Fixinggear .331 relative to the frameby this engagement, through pini341, 'will .then preclude rotation of shaft '46. On the other hand, the engagement of .pawl 325 with the notch 323 on thegear hub will result in.rotation of gear 331 whichbecause of the pawl and notch have effectively been joined. Through the idler gear 341,

the power will be transmitted to gear 343 and cause a corresponding rotation of parallel guide rods HI and H2 which have been fixed thereto. It should be notedthat the direction of rotation of the drive motor must be such as to ensure cooperation between the notches in the gear hub and the corresponding pawls.

As previously described in connection with the driving mechanism of Figures 12 and 13, rotation of the parallel rods will cause rotation of the drum and if the segment of the nut l3| is in engagement with the threads I21 will also cause axial displacements thereof.

Therefore when the lever arm 312 is in the position indicated in Figure 23, the device will be in condition for the reception of facsimile signals and the recording thereof, and when displaced through 180 will be in a position for the transmission of signals corresponding with the lights and shades of a picture.

Thus in either modification of the mechanical system, by the operation of a hand lever, I may adjust my facsimile unit to either record or transmit facsimile images.

The synchronizing principle which I have illustrated although applied to a single drum recorder, may obviously be employed upon recorders of multi-stylus type if the styli themselves are mounted upon a track which is in effect endless. Thus, if I replace the chain which carries the stylus in my facsimile unit illustrated in my copending application Ser. No. 334,404 by an endless flexible chain of uniform cross section which in addition provides facilities for slidably mounting a stylus carriage, I may again secure the benefits of synchronization without undue stopping and starting of massive parts, and without the need for a second rephasing signal.

Although I have described and illustrated my invention as applied to a drum type transmitter, it will be understood by those skilled in the art that the same principles may be applied to other well-known forms of picture transmitter systems such as the oscillating type step-by-step feed shown in my Reissue Patent No. 19,575, dated May 21, 1935 or I may employ the duplex machine functions described in my application Serial No. 318,230 by adding a lamp housing with its associated system and a photoelectric cell to convert the lights and shades of apicture line into corresponding electrical variations.

I claim:

1. A duplex facsimile apparatus comprising a drum, a fixed light beam scanning member for translating the light and shades of a picture into corresponding electrical currents, said drum being rotatable and axially movable with respect to said light beam scanning member, means for transmitting said currents, a recording stylus scanning member, means for driving said recording stylus scanning member about the circumference of said drum and in a fixed plane normal to the axis of said drum, means for impressing received facsimile signals upon said stylus, means for axially displacing said drum with respect to each scanning member, and. means for selectively causing the rotation of said drum when said apparatus is in operation as a transmitter, and locking'said drum against rotation when said apparatus is in operation as a recorder.

2. A duplex facsimile apparatus comprising a drum, a fixed light beam scanning member for translating the lights and shades of a picture into corresponding electrical currents, means for transmitting said currents, a recording stylus scanning member, means for driving said recording stylus scanning member about the circumference of said drum and in a fixed plane normal to the axis of said drum, means for receiving facsimile picture and synchronizing signals, means for maintaining said recording stylus in synchronism with said synchronizing signals, means for axially displacing said drum with respect to each scanning member when operating said apparatus to receive pictures, means for simultaneously rotating and axially displacing said drum when operating said apparatus for the transmission of pictures, comprising a source of motive power, a threaded shaft in coaxial relation with said drum and a threaded member on said drum in releasable engagement with said threaded shaft,

a cam fixed relative to said threaded shaft, means including said cam for selectively impressing said received picture signals upon said recording stylus and said synchronizing signals upon said synchronizing means when operating said apparatus for receiving pictures, and means including said cam for precluding the rotation of said threaded shaft when operating said apparatus for transmitting pictures.

3. A duplex facsimile apparatus comprising a drum, a fixed light beam scanning member operable at a distinct speed relative to said drum for translating the light and shades of a picture into corresponding electrical currents, means for transmitting said currents, a recording stylus scanning member, means for driving said recording stylus scanning member about the circumference of said drum and in a fixed plane normal to the axis of the drum at a slightly different speed relative to the speed of said light beam scanning member with respect to the drum, means whereby the over-all speed of transmitting and recording stylus scanning members relative to the drum is the same, means for receiving facsimile picture and synchronizing signals, means for supporting a sheet of sensitized material upon said drum and means impressing said received picture signals between said stylus and drum for the recording of pictures, said stylus being in juxtaposition with said sensitized material, means for supporting a picture upon said drum when operating said apparatus for the transmission of pictures, and means for releasing said recording stylus from contact with said drum.

4. A facsimile apparatus comprising a picture area, a transmitting scanning member associated therewith and operable at a first speed for translating successive unit areas of said field into picture currents varying in accordance with lights and shades of a picture to be transmitted; a receiving scanning member operable at a second speed slightly different from said first speed for translating received picture currents into corresponding lights and shades for reproduction in said picture area, means whereby the over-all speed of a complete cycle of said first and second scanning members is the same and means for selectively rendering said transmitting and said receiving scanning members operative.

5. A facsimile apparatus comprising a picture area, a transmitting scanning member associated therewith for translating successive unit areas of said field into picture currents varying in accordance with lights and shades of a picture to be transmitted; a receiving scanning member for translating received picture currents into in said first picture area,'means for selectively rendering said transmitting and said receiving scanning members operative, means operative when said transmitting scanning member is in operation for periodically generating synchronizing pulses, means for making said receiving scanning rate slightly higher than said transmitting scanning rate and means operative when said receiving scanning member is in operation for operating in response to received synchronizing pulses to maintain said receiver in synchronism with a remote transmitter and at the same over-all cyclic speed of said first mentioned transmitter.

WILLIAM G. H. FINCH. 

